Blockchain　is　a　kind　of　distributed　ledger　technology　that　upgrades　to　a　complete　storage　system　by　adding　logic　control　functions　such　as　intelligent　contracts.　With　the　changes　of　its　classification,　service　mode　and　application　requirements,　the　core　technology　forms　of　Blockchain　show　diversified　development.　In　order　to　understand　the　Blockchain　ecosystem　thoroughly,　a　hierarchical　technology　architecture　of　Blockchain　was　proposed.　Furthermore,　each　layer　of　blockchain　was　analyzed　from　the　perspectives　of　basic　principle,　related　technologies　and　research　progress　in-depth.　Moreover,　the　technology　selections　and　characteristics　of　typical　Blockchain　projects　were　summarized　systematically.　Finally,　some　application　directions　of　blockchain　frontiers,　technology　challenges　and　research　prospects　including　Smart　Cities　and　Industrial　Internet　were　given.　©　2020,　Editorial　Board　of　Journal　on　Communications.　All　right　reserved.